Systems for controlling the level of an audio signal are known. For example, systems for limiting the level of an audio signal are available in which the amplitude of the signal is measured in some way, usually by finding the peak of the signal and then deciding whether the peak is louder than some predetermined threshold. If the level is too loud, the audio signal is reduced but in most known systems this procedure often occurs too late.
Another known approach is to provide additional headroom for the input signal so that a relatively low level of signal may be maintained such that when peak values do occur their levels are still within the dynamic range of the system.
The first approach suffers from problems associated with distortion and the second approach suffers from problems associated with noise and inefficiency given that the full dynamic range of the system is unavailable for most normal applications.